Brake for bending sheet metal blanks



Oct. 27, 1964 J. P. HOFFMAN BRAKE FOR BENDING SHEET METAL BLANKS 5 Sheets-Sheet 1 Filed July 17, 1961 INVEN TOR. Jamwfffoffman. BY 5 ATTORNEY.

5 Sheets-Sheet 2 J. P. HOFFMAN BRAKE FOE BENDING SHEET METAL BLANKS Oct. 27, 1964 Filed July 17. 1961 INVENTOR. Jamas-P/foffman, BY

' ATTORNEY.

Oct, 27, 1964 J. P. HOFFMAN 3,

BRAKE FOR BENDING SHEET METAL BLANKS Filed July 17, 1961 5 Sheets$heet 3 Qfamas]? off/77012,

ATTORNEY.

Oct. 27,1964 J. P. HOFFMAN BRAKE FOR BENDING swam METAL BLANKS 5 Sheets-:Sheet 5 Filed July 17, 1961 INVENTOR. as]? H ffman,

ATTORNEY.

United States Patent 3,154,129 BRAKE FOR EENDENG EHEET METAL BLANK? James P. Hoffman, W est Valley, ELY. Filed .lluly 17, 1961, Sen. No. 124,636 23 Qlairns. (Cl. 15316) This invention relates to improvements in brakes for bending sheet metal blanks into any redetermined cross sectional outline characterized by reverse bends and bends in the same direction, the particular outline being in accordance with the indicated use of the resultant product and the sheet metal blank in which such bends are formed being of any suitable gauge for the particular job. The characterizing features of construction and operation of my improved brake are applicable to machines for the production of sheet metal articles within a wide range of useful purposes.

The machine illustrated in the drawings as an exemplilication of the invention is particularly designed for the manufacture of rocker panels for automobiles, such panels having an indefinite range of cross sectional outlines and dimensions according to the various models of automobiles as made by the various manufacturers and as changed in design from year to year. Generally speaking rocker panels are characterized by reverse bends and by bends in the same direction and the sides of the bends may range in transverse extent from one-half inch to two and one-half inches, the interior angles of the bends ranging from 80 up to 120.

Heretofore the manufacture of rocker panels has been unduly expensive as to time and equipment, the various bends requiring more than one machine or various dies from which selections must be made.

The principal object of the invention is a light weight machine of extremely simple and economical structural character which can be operated by a single mechanic with rapidity in forming the various bends in the most economical sequence of operations. Ancillary objects are a machine which, despite its lightness, will have its operating parts substantially free from distortion in consequence of the various st esses involved in the several operations and which will insure accuracy and precision in making the several bends of the predetermined degrees of angularity.

Generally speaking the brake is characterized by a novel combination of cooperating elements essentially comprising: (1) a fixed support for the blank which serves as an anvil about which the blank is bent; (2) a clamping element for holding the blank in fixed relation upon the anvil during the bending operation; (3) means directly cooperating with the clamping element for etfecting its clamping engagement with the blank or for releasing the blank to permit its removal from and its replacement upon the anvil in preparation for a following bending operation; (4) a pivotally mounted bending element operative upon the part of the blank which projects forward from the anvil and carrying a suitable handle by which it may be moved between active and inactive positions; (5) the connected relation of the clamping element, the bending element and the handle for movement as a unit toward and from the anvil; (6) means automatically operative upon the release of the clamping element for effecting the movement of the unit away from the anvil, thereby to provide for the positioning of the blank, the handle being used when the blank has been positioned to restore the unit to its normal position; (7) and a pivotally mounted member which carries the means for effecting the engagement of the clamping element with the blank and is movable to a remote inactive position when the clamping element is to be released and to an active position when the use of the clamping element is required. The brake is also char- 3,l54-,l29 Patented Get. 27, 1964;-

"ice

acterized by sundry novel structural details appertaining to certain features of the above stated combination of elements and which will appear as the description proceeds.

In the drawings:

FIGURE 1 is a plan view of the brake.

FIGURE 2 is a front elevation of the handle and the bending element by which it is carried.

FIGURE 3 is an end elevation of the brake and may be taken as representing the appearance of the brake as viewed from either end.

FEGURE 4 is a transverse sectional view on the line 44 of FIGURE 1.

FIGURE 5 is a fragmentary front elevation of the brake with parts broken away to enable illustration on an enlarged scale.

FIGURE 6 is a detail cross sectional view on the line 6-6 of FIGURE 1.

FIGURE 7 is a detail cross sectional view on the line 77 of FIGURE 1.

FIGURE 8 is a perspective view of a feature at one end of the brake for the mounting of the bending bar.

FIGURE 9 is a perspective view of a feature at the opposite end of the brake for the mounting of the bending bar.

FIGURE 10 is a detail transverse sectional view on the line ill-1t) of FIGURE 5.

FIGURE 11 is a perspective view of sundry associated parts which as a unit are movable between operative and inoperative positions.

FIGURE 12 is a detail fragmentary perspective view of a movable part of the table by which the elements of the brake are supported.

FIGURE 13 is a detail perspective view showing the trunnion mounting of the bending bar of the brake.

FIGURE 14 is a detail perspective view of elements for the mounting and support of the means for causing and maintaining the engagement of the clamping element of the brake with the blank.

In aid of the reading of this specification it is noted that in the following description and in the claims the designations front and forward and rear, rearward and behind are used. Their usage is with reference to the positions and relations of the parts as shown in FIGURE 4. Thus, front and forward connote parts or surfaces at, or directed to, the left of related parts or surfaces and rear, rearward and behind similarly connote parts or surfaces at, or directed to, the right of related parts or surfaces.

The various operating parts are carried by a table designated generally as 1 and having corner supporting legs 2 which are preferably attached to the floor by means of lugs 3 at their lower ends. The top of the table is preferably of skeleton form and includes end bars 4 and spaced longitudinal bars 5 and 5a, preferably of angle iron cross section, the bar 5a being located adjacent the front of the brake. The stacks S of the blanks from which the rocker panels are to be formed may be supported at any convenient location on the bars 5 of the table as shown by dot and dash lines in FIGURES 3 and 4.

A longitudinal anvil 6 preferably of angle iron cross section is supported at the front of the table by the end bars 4 to which it is connected as by welding. The anvil 6 has horizontal and vertical parts 7 and 7a, the active part 7 being preferably flush with the upper edges of the bars 4 and somewhat below the upper face of the bar 5a. The part 7 provides support for the blank B which is required to be bent and the part 7a depends from the part '7. The part 7 preferably has a thickness of onehalf of an inch, a width of two and one-half inches and a length of not less than eight feet, this being the length of the rocker panels of hearses and ambulances. The blank B projects forward beyond the part 7 and in the formation of the rocker panel its forwardly projecting portion is bent in a series of successive operations about the straight elongated front corner edge of the part 7. The front or edge face of the part 7 is preferably inclined downward and inward as shown at 8 in FIGURES 4 and 6, whereby the projecting portion of the blank B may be bent downward about the front corner edge to a maximum extent, that is to say an extent in which it forms an included angle of 80 with the portion of the blank which rests upon the part 7.

During the bending operations the blank B is clamped upon the part 7 of the anvil 6 by a clamping element 9 coextensive with the anvil and which is preferably of angle iron cross section. The clamping element 9 has a horizontal part 10 and a vertical part 11, the part 11 overlying the part 7 of the anvil 6 and engaging the blank B preferably in immediate adjacency to the upper front edge of the part 7 of the anvil 6.

The part of the blank which projects forward from the anvil is bent downward by a bending bar 12 coextensive with the anvil 6 and the clamping element 9 and which is preferably of angle iron cross section, having a vertical part 13 and an horizontal part 14. The bending bar 12 is movable pivotally between a normal or inactive position shown at X in FIGURE 6 and a number of active positions, in any one of which it effects the bending of the blank and one of which is shown in dot and dash lines at Y in FIGURE 6. The vertical part 13 of the bending bar 12 is adjacent to the vertical part 11 of the clamping element 9 and is located under the horizontal part 10 of the clamping element 9. The horizontal part 14 of the bending bar 12 is the active part, i.e., the part which effects the bending of the blank and extends forward from the part 7 of the anvil 6. The bending bar 12 is provided with end trunnions 15 (FIGURES 2 and 7) for its pivotal mounting. For such mounting similar brackets 16 (FIGURES 8 and 9) are provided at the front of the table adjacent its ends and are formed with annular bearing parts 17 having openings 18 for the trunnions 15. The brackets 16 are of general L-shape and have vertical parts 19 and rearwardly extending horizontal parts 20, the parts 19 being connected to the vertical part 11 of the clamping element 9 by bolt fastenings 21. The bracket 16 at the right end of the table, FIGURE 1 being considered, carries a vertical index plate 22 having an arcuate series of calibrations 23 and the opposite bracket 16 carries a vertical latch plate 24 having an arcuate series of openings 25 severally to receive a latch bolt 26 (FIGURE 2) carried by the handle to be later described. The part 7 of the anvil 6 is formed with recess 7b (FIGURE 7) to accommodate the bearing parts.

During the operation of the bending bar 12 substantial stress in the forward direction is placed upon the clamp ing element 9. In order to eliminate any risk of resultant distortion of the clamping element the brackets 16 are preferably reinforced during the bending operation. For this purpose the horizontal parts of the brackets 16 terminate in downward extensions 27 having inner cam faces 28 as best shown in FIGURES 6 and 7, the extensions 27 in the normal positions of the parts (FIG- URE 4) being spaced rearward of the anvil 6 to accommodate reinforcing plates 29 attached as by bolt fastenings 311 to the vertical part 7a of the anvil 6. At their upper ends the plates 29 have their rear faces inclined as at 31 to function as cams for cooperation with the cam faces 28 of the extensions 27.

The trunnions 15 are suitably offset from the bending bar 12, their longitudinal axes coinciding with the line formed by the meeting of the outer faces of the vertical and horizontal parts 13 and 14. For the connection of the trunnions to the bending bar 12 radially extending arms 32 are provided, these resembling crank arms, being rigidly connected to the trunnions as by welding or integral formation, and being provided at their upper ends with lateral inwardly projecting crank-like extensions 33 which lit in the inside corners provided by the parts 13 and 14 of the bending bar and are welded to such parts. The part 14 of the bending bar carries near its ends forwardly projecting plates 34 which serve for the attachment of a handle 35 preferably of tubular construction and inverted V-shape. The handle is attached at its ends to the plates 34 and for reinforcing purposes is preferably provided with a number of depending posts 36 which are rigidly connected to the horizontal part 14 of the bending bar 12, the connections consisting of plates 37, preferably of channel cross section, to which the posts 36 are welded, the plates in turn being welded to the upper face of the part 14.

The bending bar 12, the clamping element 9, the brackets 16 and the handle 35 as interconnected in the manner above described constitute a unit U which is movable to a position above the anvil 6 to enable the original placement or the replacement or rearrangement of the blank B relatively to the anvil. When the blank B has been originally placed upon the anvil or following a bending operation has been repositioned upon the anvil, the unit, while being in raised position, is lowered by means of the handle 35 whereby its several parts are in the normal position shown in FIGURE 4 in readiness for a bending operation. It will be noted that when the unit is thus lowered the came 31 by their hearing engagement with the cam faces 28 of the extensions 27 exert a stress in the rearward direction upon the brackets 16 which neutralizes the stress upon the clamping element 9 and the bending bar 12 in the forward direction resultant from the bending operation.

The mounting of the unit U for movement between its normal position and its position above the anvil 6 includes a pair of supporting arms 33 (FIGURES 3, 5 and 11) in adjacency to the respective end bars 4, each arm 38 having a supporting pivotal connection 39 located suitably rearwardly of the anvil to the corresponding end bar 4, the connections 39 being coaxial. At their front ends the arms 38 are connected, as by welding, to the ends of the clamping element 9 and at their rear ends are connected by tensioned coil springs 40 to frame bars 41 of the table 1. During the use of the brake the clamping element 9 is securely held in operative position by a means to be described and which is manually operated to release the clamping element whereupon the springs 49 are utilized to move the unit U to its elevated position above and remote from the anvil 6.

It is desirable, however, that the unit U in its normal position be relieved from the pull of the springs 4-19 in order that there may be no stress opposed to the means for holding the clamping element. For this purpose tensioned spring links 42 are preferably utilized, each link 42 having its forward end connected to a pin 43 carried by the associated arm 33 and its rear end connected to a pin 44 provided upon a bracket 45 which is carried by the corresponding frame bar 4. The pins 43 and 44 are so arranged that the springs 42 in the normal position of the unit U as shown in FIGURE 4 are located below a position of dead center with reference to the pivots 39 of the arms 3%, thereby to relieve the unit U from the pull of the springs 40. When the clamping element 9 is released by its holding means the handle 35 is moved manually in the rearward direction about the pivots 39 through the few inches needed, in consequence of the upward movement of the bars 33, to bring the springs 12 to a position above dead center with reference to the pivots 39 whereupon the springs 49 are effective to move the unit U to its raised position in which it is sufficiently remote from the anvil to enable the placement or replacement of the blank B. In order to re ulate the tension of the springs 42 the brackets 45 are preferably positionally adjustable along the length of the bars 4 and for this purpose are provided with headed screws as which extent through horizontal slots 47 in the bars 4, the screws 46 being normally tightened whereby their heads bear with pressure upon the bars 4 and hold the brackets 45 against displacement.

It is desirable that the bending bar 12 be securely held in any selected position to which it may be moved and any suitable means may be provided for this purpose, the latch bolt 2e (FIGURE 5) being an example. The belt is movable through a guiding and supporting sleeve 48 carried by the handle 35 and is engageable in any one of the closely associated openings 25, its engaging movement being preferably etfected by a loading spring 49. The latch bolt is withdrawn from an opening 25 by a fingerpiece 5t) pivotally mounted upon the handle 35 and connected to the latch bolt by a suitable linkage 51.

The plate 34- which is adjacent the index plate 22 is provided with an attached finger 52 which extends as a pointer toward the calibrations 23. The specific are required for the completion of a particular bending operation is indicated by the coincidence of the pointer 52 with a particular calibration on the index plate 22. The mechanic is thereby advised of the precise limitation of the operative movement of the bending bar 12 which is required for a particular bending operation. With this limitation determined he positions a stop to be later described which will positively effect the limitation. When the limitation of the bending movement of the bar 12 has been effected the mechanic thereupon effects th release of the clamping element 9 and the movement of th unit U to its upper position remote from the anvil 6 in preparation for the removal of the blank B from the anvil and its repositioning upon the anvil if a further bending operation be required or, if the article, eg. the rocker panel, be then completely formed, in the positioning of another blank 13 upon the anvil.

According to the particular article to be fashioned by the brake the blanks will vary in dimensions between their front and rear edges. In the use of the brake the degree .to which the blank may project rearward from the front edge of the part 7 of the anvil 6 is predetermined for the several bending steps and varies from step to step. In some instances the blank may project at various distances rearwardly from the anvil 6 and in other instances its rearward projection from the front edge of the anvil 6 may be variously limited to a position in which the rear edge of the blank is within the area of the upper face of the blank supporting part 7 of the anvil 6. In the limitation of the projection of the blank rearward from the front edge of the part '7 of the anvil 6 the longitudinal bar 5a may be utilized and this bar is therefore mounted for positional adjustment in the direction of the length of the end bars 4. For this purpose the bar 5a. has its end portions cut away to conform to the angle iron outline of the bars 4 and is fixed in position relative to the bars 4 by L-shaped fasteners 53 (FIGURES 4 and 12) having at their lower ends angular extensions 54 which extend under the lower edges of the vertical parts of the bars a and having their upper end portions threaded and projecting through openings in the horizontal parts of the bar 5a. Thumb nuts 55 are fitted upon the threaded portions of the fasteners 53 and by engagement with the upper face of the bar 5:: are used to clamp it in a particular position upon the bars 4. When it is necessary to change the position of the bar 5a the thumb nuts 55 are backed off and the bar is moved forward or rearward along the bars 4 to an extent which accords with the required positional adjustment.

In its function of limiting the projection of the blank rearward from the front edge of the blank supporting part 7 of the anvil 6 the bar 5a is used in association with a pair of stop elements 56 (FIGURES 4 and 12) arranged at opposite sides of a central fore and aft plane of the brake. Each stop element 56 has a part 57 for attachment to the bar 5a and an extension 58 which projects at a suitable angle from the part 57. Each stop has two positions in one of which its part 57 extends vertically and in the other of which it extends horizontally. The stop 56 in its vertical position is attached by a bolt and nut fastening 59 to the vertical part of the bar 5a and in its horizontal position is attached by the same fastening to the horizontal part of the bar 5a. The angle of the extension 58 relatively to the part 57 is such that in the vertical position of the stop 55 it extends downward and rearward and in the horizontal position of the stop 56 it extends downward and forward. The stop 56 is shown in its vertical position in FIGURES 4 and 12 and in its horizontal position (in broken lines) in FIG- URE 12. In its vertical position the attachment part 57 extends above the supporting part 7 of the anvil 6 and limits the projection of the blank rearward from the anvil, the bar 5a being positionally adjustable along the end frame bars 4 to accord with any required degree of rearward projection of the blanks from the anvil. Absent the stop as the vertical part of the bar 5a may be used for this puropse. In the horizontal position of the stop 56 the extension 58, as shown in FIGURE 12, projects forward and downward from the part 57 and its front end rests upon the anvil a whereby its front edge face serves the stop function and limits the projection of the blank rearward from the front upper edge of the anvil to any determined position within the area of the part 7.

The stop for limiting the movement of the bar 12 in the bending operation includes an abutment lug 6t? carried by the plate 34 which adjoins the index plate 22, i.e. the plate 34 at the right, FIGURE 1 being considered. The lug eh projects laterally and downward from its supporting plate 34 to a position in which at the completion of the bending operation it will engagethe end of a positionallly adjustable stop pin 61. As shown, the pin 61 is in the form of a screw tapped through an opening in a downward extension 62 of the reinforcing plate 29 at the corresponding end of the brake and having at its rear end a fingerpiece by means of which it may be turned. The mechanic first moves the bar 12 to the precise position required for the contemplated bending operation as indicated by the coincidence of the pointer 52 with a particular calibration on the index plate 22. Thereupon, with the bar 1.2 held in this position by means of the handle 35, the pin s1 is turned by means of its fingerpiece until it is brought to a position in which its end will contact the abutment lug so. The handle 35 is then raised to bring the unit U to a position above and remote from the anvil 6 to enable the positioning of the blank. When the blank has been clamped in its determined position the handle 35 is swung downward to cause the operation of the bending bar 12, its downward movement being continued until it is arrested by the engagement of the lug against the end of the screw 61.

The means which directly cooperates with the clamping element in effecting its function or its release is provided in duplicate, each such means being indicated generally at M and the two means M being arranged symmetrically at opposite sides of a central fore and aft plane of the brake with their operating features within easy reach of the mechanic when standing at a central position in front of the brake.

Each means M includes an arm 63 of substantial 6- shape in outline and of T-shape in cross section, the arm thereby including an outwardly directed flange 64. At its lower end the flange as has an extension 65 which provides for its pivotal support at a point suitably below the top of the table. For the support of the arm 63 a pair of vertical hangers 66 is provided, these depending from the anvil 6 to which they are connected, as by welding, at their upper ends. The hangers 66 are preferably of angle iron cross section and have coplanar vertical parts 67 and forwardly projecting parts in spaced parallel relation, the hangers 66 at their lower ends being provided with forwardly projecting lugs coplanar with the parts 68. The flange extension 65 extends between the lugs 69 and rearward beyond the hangers 66 and is pivoted to the lugs 69 as at 7h. In the normal position of the parts in which the means M is in an elevated operative position the upper end of the arm 63 abuts the front edge face of the clamping element 9. In the lower inoperative position of the means M in which the clamping element 9 is released, the rearwardly projecting extension 65 engages a transverse stop plate 71 secured for positional adjustment upon the coplanar parts 67 of the hangers 66. For such positional adjustment the parts 67 are formed with vertical slots 72 and the stop plate '71 is secured by bolt fastenings 73, the bolts extending through the slots 72. In order to permit the bending of the blank to an included angle of 80 as provided for by the inclined front edge face 8 of the anvil part 7, the parts 63 of the hangers as have front edge faces 74 which are inclined in conformity to the edge face 8 of the part 7.

The means M includes a feature P which is effective to cause the clamping engagement of the clamping element 9 or to effect its release when the unit U is to be moved to its upper inoperative position. This feature includes a two-armed lever 75 pivoted at an intermediate point as at 76 to the flange 64. The lever 75 has an arm 77 which projects rearward from the pivot '76 and carries a pair of screws '78 preferably having their lower ends pointed for engagement in the recesses 79 in the part of the clamping element. The lever 75 also has an arm 80 which projects forward from the pivot 77 and is conected to a toggle 31. The toggle 81 consists of a pair of lower links 82 and a pair of upper links 83, the toggle being operated by a handle 84 The links 82 are pivotally connected at their lower ends to the flange 54 by a bolt 85 upon which the handle 84 is mounted, the bolt 85 serving as a pivot for the handle. The links 32 are also connected at their upper ends to the links 83 by a bolt 86, the links 83 being pivotally connected at their upper ends by a bolt 87 to the forward end of the arm 86.

With the parts in their normal position as shown in FIGURE 4, the pivotal connection 86 of the toggle links 82 and 83 will be in a position beyond dead center (at the right, FIGURE 4 being considered) whereby the lever 75 through the screws 78 will cause the clamping element 9 to bear upon the blank with clamping pressure and thereby securely hold the blank during the bending operation. The function of the feature F is twofold, viz. first to actuate the lever 75 to hold the clamping element 9 upon the blank or to disengage the lever 75 from the clamping element 9, and second to move the arm 63 between its raised and lowered positions. With the parts in the normal relation shown in FTGURE 4, and assuming the bending operation to have been completed, the handle 34 is swung forward about its pivot 85 and in the first part of its forward movement actuates the toggle whereby the pivot 86 is moved to the opposite side of dead center as shown in broken lines. When the pivot 86 passes forward beyond dead center, i.e. to the left of dead center, the lever 75 disengages the clamping element 9. The continued forward movement of the handle 84 moves the arm 63 to its lower position as shown in broken lines in FIGURE 4 and is continued until the extension as of the flange s4 engages the stop plate 71. With the arm 63 thus held in its lower position the handle 35 is operated in the manner above described whereby the unit U is moved by the springs 46 to its elevated position in which it is above and remote from the anvil 6. The blank may then be removed from the anvil and repositioned or another blank may be substituted whereupon the handle 35 is moved downward to bring the unit U into its normal position. When this has been done the handle 84 is moved rearward, first to raise the arm 63 to its normal position wherein its upper edge abuts the clamping element 9, and thereafter as continued about its pivot 85 to actuate the toggle 81 in its function of causing the lever to apply clamping pressure to the clamping element and of maintaining the lever 75 in its pressure appiying position.

When the bending operations are applied to thicker 0r heavier blanks stresses are set up which tend to bow or distort the bending bar in a forward direction with a resultant impairment of the accuracy of the bending operation. In order to overcome the adverse effects of such stresses the bending bar may be reinforced by features R (FIGURE 10) which are provided in duplicate and at suitable distances at opposite sides of the central fore and aft plane of the brake.

Each feature R consists of an arcuate plate 88 carried by the bending bar 12 and a companion keeper plate 89, itself reinforced by a central rib 94), carried by the clamping element 9 and attached, as by welding, to the under face of the part it the plate 39 having an inner face 91 curved in conformity to, and bearing upon, the plate 88. The plate 33 is fitted in recesses in the parts 13 and 14 of the bending bar 12 to which it is secured as by welding and projects to a slight extent as at 92 beyond the part 13 of the bending bar 12. With the bending bar in its normal position, as shown in broken lines in FIG- URE 10, the projecting part 92 of the plate 88 is accommodated in an opening 93 in the vertical part 11 of the clamping element 9.

FIGURE 4 shows the brake inactive, that is to say with the various parts in what has been called their normal positions but without a blank B upon the anvil 6. With the parts disposed as shown in FIGURE 4 the following is a resume of the operations required in the use of the brake: The mechanic, knowing the angle of the initial bend, moves the handle 35 about its trunnions 15 as an axis with resultant turning movement of the bending bar T2 through the degree required for the particular bend and thereupon sets the stop pin 61 in its proper position. By means of the handle 84 the means M is then moved to its lower position until its movement is arrested by the stop plate 71, thereby to release the clamping element 9 from the pressure of the lever '75. The handle 35 is then used to raise the unit U to its position above and remote from the anvil 6. The blank B is thereupon positioned upon the anvil in readiness for the initial bending operation. The unit U is then lowered to position the clamping element upon the blank B after which the means M is raised until the arm 53 abuts the clamping element whereupon the handle 84 is operated to cause the lever 75 to hold the clamping element in engagement with the blank, such adjustment of the screws 78 being made as will accord with the thickness of the blank. The handle 35 is then moved about the trunnions 15 as an axis with resulting movement of the bending bar 12 in the initial bending operation, the movement of the bending bar being continued until it is arrested by the stop pin 61. The handle 3-5 is then used to move the bending bar 12 back to its initial position in which it abuts the clamping element 9. The means M is then lowered to release the clamping element 9 whereupon the handle 35 is moved upward about the pivots 39 as an axis thereby to bring the unit U to its position above and remote from the anvil 6. Thereupon the blank is repositioned upon the anvil in preparation for the next bending step. The sequence of operations is repeated until the various bends of the blank B have been completed. The article in its ultimate form is then removed from the anvil and another blank B is positioned in readiness for the initial bending operation in the next sequence of such operations.

I claim:

1. A brake for bending sheet metal blanks comprising in combination: an anvil having a horizontal supporting face with a straight elongated front edge and upon which a sheet metal blank may be placed in a position appropriate for a predetermined bending operation about said edge, the blank in such position projecting forward from the anvil; a unit movable between a position above and remote from the anvil and a normal position in which its parts are in operative relation to the anvil, the unit including brackets adjacent the ends of the anvil, a clamping element extending between and carried by the brackets and in the normal position of the unit bearing upon the blank as positioned upon the anvil, and a bending bar coextensive with the anvil and in the normal position of the unit projecting forward from and adjoining the front face of the anvil and bearing upon the part of the blank which projects forward from the anvil, the bending bar having at each of its ends coaxial journalled mountings in the brackets and thereby being supported by the brackets for downward movement from a normal inactive position, the bending bar in its downward movement effecting the bending of the blank; a pair of supporting arms for the unit having their ends connected to a fixed part of the unit; coaxial pivotal mountings for the supporting arms located at a suitable distance rearwardly of the anvil; and means cooperative with the clamping element to cause it to apply and maintain clamping pressure upon the blank and to release the blank from such pressure, the means comprising an arm mounted for movement about a pivot suitably below the anvil and movable between a normal elevated position in which it is maintained during the bending operation and a lowered position when the bending operation has been completed, and a manually controlled mechanism carried by the arm and actuatable when the arm is in its elevated position which includes a lever element mounted for movement between operative and inoperative positions, the lever element in its operative position having maintained engagement with the clamping element to cause it to apply clamping pressure to the blank and in its inoperative position being remote from the clamping element to enable the movement of the arm to its lower position and thereby to enable the unit to be moved to its upper position remote from the anvil.

2. A brake for bending sheet metal blanks as set forth in claim 1 wherein the clamping element is of angle iron cross section and has a vertical part and a forwardly projecting horizontal part, the vertical part in the normal position of the unit bearing upon the part of the blank that rests upon the anvil, the bending bar is arranged below the horizontally projecting part of the clamping element, is of angle iron cross section, has a vertical part and a horizontal part, and has a normal inactive position in which its vertical part abuts the vertical part of the clamping element and its bearing upon the blank is effected by the horizontal part, and the lever element of the means cooperative with the clamping element bears upon the horizontal part of the clamping element.

3. A brake for bending sheet metal blanks as set forth in claim 2 wherein the coaxial journalled mountings of the bending bar consist of trunnions carried by the bending bar at its ends with their longitudinal axes coinciding with the line formed by the meeting of the outer faces of the vertical and horizontal parts of the bending bar, a radially extending arm carried by and rigidly connected to each trunnion and an inwardly projecting crank-lik extension carried by each arm, the extensions fitting in the inside corners provided by the vertical and horizontal parts of the bending bar and being rigidly secured to such parts, and annular bearing parts provided on the brackets and having openings in which the trunnions are rotatably mounted.

4. A brake for bending sheet metal blanks as set forth in claim 1 wherein the anvil has a front edge face which is inclined downward and inward at an angle of substantially 80 to its horizontal supporting face.

5. A brake for bending sheet metal blanks as set forth in claim 1 wherein the unit includes a handle extending from end to end of the bending bar and having its ends rigidly connected to the end portions of the bending bar, the handle being available to effect the movements of the bending bar and of the unit.

6. A brake for bending sheet metal blanks as set forth in claim 5 wherein one of the brackets carries a latch plate and the handle carries a latch bolt, a movably mounted fingerpiece and a linkage connecting the fingerpiece to the latch bolt, the latch plate being formed for cooperation with the bolt whereby the handle may be held in a predetermined position.

7. A brake for bending sheet metal blanks as set forth in claim 1 wherein the bending bar is provided with an abutment lug which projects forward from the bending bar in the normal position of the unit and a positionally adjustable stop pin is provided for engagement with the abutment lug when the bending bar has been moved through the are necessary for effecting a particular bending operation, thereby to limit the operative turning movement of the bending bar.

8. A brake for bending sheet metal blanks as set forth in claim 1 wherein the supporting arms for the unit are connected at their rear ends to tensioned coil springs which are operative to effect the movement of the unit to its elevated position above the anvil.

9. A brake for bending sheet metal blanks as set forth in claim 8 wherein a supporting table is provided which is composed of end bars and longitudinal bars, the anvil is fixedly connected at its ends to the end bars, the coaxial pivotal mountings of the supporting arms are connected to the end bars and the table has fixed parts below its longitudinal bars to which the tensioned coiled springs are connected.

10. A brake for bending sheet metal blanks as set forth in claim 1 wherein the supporting arms for the unit are connected at their rear ends to tensioned coil springs which are operative to effect the movement of the unit to its elevated position above the anvil and a tensioned spring link is provided in association with each supporting arm and has its forward end connected to the supporting arm at a point in advance of its pivot and its rear end having a fixed connection, the points of connection of the spring link being so located that when the unit is in its normal position the spring link has a position below dead center as constituted by the pivot of the arms and when the unit is in its position above and remote from the anvil it has a position above dead center as constituted by the pivot of the arms.

11. A brake for bending sheet metal blanks as set forth in claim 10 wherein a supporting table is provided which is composed of end bars and longitudinal bars, the anvil is fixedly connected at its ends to the end bars, the coaxial pivotal mountings of the supporting arms are connected to the end bars, the table has fixed parts below the longitudinal bars to which the tensioned coiled springs are conected, and the fixed connections at the rear ends of the tensioned spring links are carried by the end bars at a point rearwardly beyond the rear ends of the supporting arms.

12. A brake for bending sheet metal blanks as set forth in claim 1 wherein one of the brackets carries a plate provided with an arcuate series of calibrations and the bending bar at its end adjacent such bracket is provided with a pointer directed toward the calibrations.

13. A brake for bending sheet metal blanks as set forth in claim 1 wherein the brackets are provided with rearwardly extending horizontal parts having downward terminal extensions fashioned with inner cam faces and spaced rearward of the anvil and the anvil carries reinforcing plates having their upper end portions fitted in the space between the anvil and the downward extensions and formed with inclined faces to function as cams for cooperation with the cam faces of the extensions, thereby to counteract stresses in a forward direction upon the clamping element during the bending operation.

14. A brake for bending sheet metal blanks as set forth in claim 1 wherein the bending bar is reinforced at suitable distances from and at opposite sides of the central fore and aft plane of the brake by means which in each instance comprises an arcuate plate carried by the bending bar and a companion keeper plate carried by the clamping bar, the keeper plate having its inner face curved in conformity to and bearing upon the arcuate plate.

15. A brake for bending sheet metal blanks as set forth in claim 1 wherein means is provided for limiting the degree to which the blank projects rearward beyond the front edge of the anvil.

16. A brake for bending sheet metal blanks as set forth in claim 15 wherein the means includes a longitudinal bar rearward of, parallel to and coextensive with the anvil which bar is mounted for positional adjustment between greater and less distances rearward from the anvil.

17. A brake for bending sheet metal blanks as set forth in claim 15 wherein the means includes a longitudinal bar rearward of, parallel to and coextensive with the anvil and mounted for positional adjustment between greater and less distances rearward from the anvil, and the bar carries stop elements at suitable distances from and at opposite sides of the central fore and aft plane of the brake, each stop element having a part for attachment to the bar and an extension part and being mounted upon the bar in vertical or horizontal positions, the stop elements as mounted in vertical positions projecting above the horizontal face of the anvil and as mounted in horizontal positions having their extensions overlying the horizontal face of the anvil.

18. A brake for bending sheet metal blanks as set forth in claim 15 wherein a supporting table is provided which is composed of end bars and longitudinal bars, the anvil is fixedly connected at its ends to the end bars, the means for limiting the degree to which the blank projects rearward beyond the front edge of the anvil includes a longitudinal bar rearward of, parallel to and coextensive with the anvil and the longitudinal bar is provided at its ends with means for holding it in clamped relation to the end bars, such means in each instance including a nut which may be backed oif to enable the longitudinal bar to be positioned nearer to or further from the anvil.

19. A brake for bending sheet metal blanks as set forth in claim 1 wherein a supporting :table is provided which is composed of end bars and longitudinal bars, the anvil is fixedly connected at its ends to the end bars and the coaxial pivotal mountings of the supporting arms are connected to the end bars.

20. A brake for bending sheet metal blanks as set forth in claim 1 wherein the arm mounted for movement about a pivot below the anvil has a rearward extension beyond its pivot and a stop plate is provided for engagement by the extension to limit the downward movement of the arm.

21. A brake for bending sheet metal blanks as set forth in claim 1 wherein the manually controlled mechanism consists of a toggle having pivotally connected upper and lower links, the lower links being pivoted to the arm, a lever pivoted at a point intermediate its length to the arm 12 of the means cooperative with the clamping element and having its rear end formed for engagement with the clamping element to maintain it in clamping relation and its front end pivoted to the upper links of the toggle, and a handle pivoted to the arm coaxially with the lower links of the toggle.

22. A brake for bending sheet metal blanks as set forth in claim 21 wherein the arm of the means cooperative with the clamping element when in its raised position abuts the clamping element.

23. A brake for bending sheet metal blanks comprising in combination: an anvil having a horizontal supporting face with a straight elongated front edge and upon which a sheet metal blank may be placed in a position appropriate for a predetermined bending operation about said edge, the blank in such position projecting forward from the anvil; a unit movable between an elevated position remote from the anvil and a normal position in which its parts are in operative relation to the anvil, the unit including brackets adjacent the ends of the anvil, a clamping element extending between and carried by the brackets and in the normal position of the unit bearing upon the blank as positioned upon the anvil, and a bending bar coextensive with the anvil and in the normal position of the unit projecting forward from the anvil, the bending bar adjoining the front edge face of the anvil and bearing upon the part of the blank which projects forward from the anvil, the bending bar having at each of its ends coaxial journalled mountings in the brackets and thereby being supported by the brackets for downward movement from a normal inactive position, the bending bar in its downward movement effecting the bending of the blank; movably mounted means connected to a fixed part of the unit for the support of the unit in either of its two positions; and means cooperative with the clamping element to cause it to apply and maintain clamping pressure upon the blank and to release the blank from such pressure, the means comprising an arm mounted for movement between the elevated position in which it is maintained during the bending operation and a lowered position when the bending operation has been completed, and a manually controlled mechanism carried by the arm and actuatable when the arm is in its elevated position which includes a lever element mounted for movement between operative and inoperative positions, the lever element in its operative position having maintained engagement with the clamping element to cause it to apply clamping pressure to the blank and in its inoperative position being remote from the clamping element to enable the movement of the arm to its lower position and thereby to enable the unit to be moved to its elevated position remote from the anvil.

References (Iited in the tile of this patent UNITED STATES PATENTS 1,721,698 Krueger July 23, 1929 2,014,485 Themar Sept. 17, 1935 2,343,441 Babcock et al. Mar. 7, 1944 2,438,319 Kilham Mar. 23, 1948 2,474,683 Linder June 28, 1949 

1. A BRAKE FOR BENDING SHEET METAL BLANKS COMPRISING IN COMBINATION: AN ANVIL HAVING A HORIZONTAL SUPPORTING FACE WITH A STRAIGHT ELONGATED FRONT EDGE AND UPON WHICH A SHEET METAL BLANK MAY BE PLACED IN A POSITION APPROPRIATE FOR A PREDETERMINED BENDING OPERATION ABOUT SAID EDGE, THE BLANK IN SUCH POSITION PROJECTING FORWARD FROM THE ANVIL; A UNIT MOVABLE BETWEEN A POSITION ABOVE AND REMOTE FROM THE ANVIL AND A NORMAL POSITION IN WHICH ITS PARTS ARE IN OPERATIVE RELATION TO THE ANVIL, THE UNIT INCLUDING BRACKETS ADJACENT THE ENDS OF THE ANVIL, A CLAMPING ELEMENT EXTENDING BETWEEN AND CARRIED BY THE BRACKETS AND IN THE NORMAL POSITION OF THE UNIT BEARING UPON THE BLANK AS POSITIONED UPON THE ANVIL, AND A BENDING BAR COEXTENSIVE WITH THE ANVIL AND IN THE NORMAL POSITION OF THE UNIT PROJECTING FORWARD FROM AND ADJOINING THE FRONT FACE OF THE ANVIL AND BEARING UPON THE PART OF THE BLANK WHICH PROJECTS FORWARD FROM THE ANVIL, THE BENDING BAR HAVING AT EACH OF ITS ENDS COAXIAL JOURNALLED MOUNTINGS IN THE BRACKETS AND THEREBY BEING SUPPORTED BY THE BRACKETS FOR DOWNWARD MOVEMENT FROM A NORMAL INACTIVE POSITION, THE BENDING BAR IN ITS DOWNWARD MOVEMENT EFFECTING THE BENDING OF THE BLANK; A PAIR OF SUPPORTING ARMS FOR THE UNIT HAVING THEIR ENDS CONNECTED TO A FIXED PART OF THE UNIT; COAXIAL PIVOTAL MOUNTINGS FOR THE SUPPORTING ARMS LOCATED AT A SUITABLE DISTANCE REARWARDLY OF THE ANVIL; AND MEANS COOPERATIVE WITH THE CLAMPING ELEMENT TO CAUSE IT TO APPLY AND MAINTAIN CLAMPING PRESSURE UPON THE BLANK AND TO RELEASE THE BLANK FROM SUCH PRESSURE, THE MEANS COMPRISING AN ARM MOUNTED FOR MOVEMENT ABOUT A PIVOT 